Bad service

My Ipad bill is R399 per month and for the first time this month in February Vodacom charged me R399.04 and nobody can explain the over charging. I took a contract of a Galaxy Tab of R 89.00 and upon receipt I phoned Vodacom and cancelled the contract within 2 days. I begged Vodacom twice on 09/01/15 and 19/01/15 to come fetch the device as I did not want the contract and the device at all and eventually they came to collect it, I have been charged R89.00 and R 55.64 for a device that I returned. So why was I charged for something which I do not have a contract for and have long returned it to Vodacom through RAM. I want my money back credited into my account as it cannot take more than 72 hours to deal with tis query by Mandlankosi Bhengu.